100% in trials to me indicates a few things (along with the fact you only have three classmates):
either your exams are non-standardised (school-written exams), and your exams are easy,
OR you are a genius, and get 100% in every exam.
It is highly unlikely you will get 100% raw in externals. I'm sure it does happen, with some child genius, but it really is unheard of. To exaggerate the magnitude of difficulty in extension 2, around a 74 raw becomes a ~90 mark.
So here is some of your issues:
1. Your tasks are most likely easy.
2. Your task marks don't matter, only your rank does. This is intended so that schools who set easy exams aren't aided.
3. You go to a relatively low-grade school, or a small rural school, hence the low numbers in extension 2 (this means that your cohorts performance years prior is likely to be average).
I have to make a lot of assumptions here, because you've provided us no detail. If you get 100 in the Extension 2 HSC exam as well as all your assessments, I'm sure you would have a shot at the state rank. But, with the info you've provided, it seems more like your co-ordinator is setting exams that are far too easy, or you go to a school full of geniuses.